生物质燃料是唯一可再生的零碳燃料，将对我国实现双碳目标作出重要贡献。生物质资源种类繁多，农林废弃物是主要的可利用生物质资源。不同生物质的外观性状存在较大差异，燃烧特性也不尽相同。在实际应用中，一般并不会区分不同的生物质，而是混在一起燃烧利用。目前，对混合生物质燃料燃烧特性及污染物排放特性的研究较为缺乏。针对生物质混合燃烧这一普遍存在且长期被忽视的现象，本研究从粉末、单个颗粒、颗粒集群三个层次展开研究，揭示了混合生物质燃料燃烧和污染物排放特性的变化规律，通过实验研究和理论计算分析了背后的原因，给出了混合生物质燃料发展的指导规则。主要学术贡献如下：（1）以花生壳和锯末分别作为农林生物质资源的代表物，在热重分析平台上通过粉末级别的热重实验，量化了草本类生物质与木本类生物质混合燃烧存在的协同效应。基于热重曲线，首次量化了锯末与花生壳的混合比例对热解和燃烧过程的特征参数、动力学参数、热力学参数的影响。基于红外气体分析技术，发现混合燃料没有改变主要气体产物的类型。（2）以花生壳、锯末为例，研究了不同种类生物质混合颗粒燃料的燃烧特性，用实验和计算数据综合分析了压缩成型过程对单个颗粒燃料燃烧性能的影响。以玉米秸秆的四个部位为例，采用正交实验研究了部位、粒径分布、成型压力对燃烧性能的影响。基于正交实验结果，从玉米秸秆物尽其用的角度出发，研究了玉米秸秆不同部位混合颗粒燃料的燃烧特性。（3）基于户用生物质炉具和污染物测量系统，开展了混合生物质颗粒燃料的真实燃烧实验。首次明确给出CO、NOx两种典型污染物排放特性与燃料综合燃烧指数、含氮量之间的关系，可以帮助指导生物质混合燃料的设计，为生物质混合燃料产业的健康发展提供了理论依据。
Biomass fuel is the only renewable fuel and will make an important contribution to achieving carbon peaking and carbon neutrality goals. There are many kinds of biomass resources, and agricultural and forestry wastes are the main utilizable biomass resources. The appearance and combustion characteristics of different biomass are different. In practical applications, different biomass fuels are usually mixed and burned together. At present, the research on combustion and pollutant emission characteristics of mixed biomass fuels is relatively lacking. Concentrating on the phenomenon of mixed biomass combustion, which is common and has been ignored for a long time, this study conducted research from three levels: powder, single pellet, and pellet cluster, revealed the changing rules of combustion characteristics and pollutant emission characteristics of mixed biomass fuel, analyzed the reasons behind the experimental research and theoretical calculation, and gave the guiding rules for the development of mixed biomass fuel. The major academic contributions are as follows:(1) Taking peanut shell and wood sawdust as representatives of agricultural and forestry biomass resources, the synergistic effect of mixed combustion of herbaceous biomass and woody biomass was quantified on a thermogravimetric analysis platform. Based on the thermogravimetric curves, the effects of the mixing ratio of wood sawdust and peanut shell on the characteristic parameters, kinetic parameters, and thermodynamic parameters of pyrolysis and combustion were quantified for the first time. Based on infrared gas analysis technology, it was found that the mixed biomass fuel did not change the type of main gas products.(2) Taking peanut shells and wood sawdust as examples, the combustion characteristics of mixed pellet fuels made from different kinds of biomass were studied, and the effects of the compression process on the combustion performance of single pellets were comprehensively analyzed with experimental and calculation data. Taking four fractions of corn stalk as an example, the effects of fractions, particle size distribution, and molding pressure on combustion performance were studied by orthogonal experiment. Based on the results of the orthogonal experiment, the combustion characteristics of mixed pellet fuel made from different fractions of corn stalk was studied to maximize the utilization of corn stalk.(3) Based on household biomass stove and pollutant measurement system, the real combustion experiment of mixed biomass pellet fuel was carried out. For the first time, the relationship between the emission characteristics of two typical pollutants (CO and NOx) and fuel characteristics (comprehensive combustion index and nitrogen content) is clearly given, which can help guide the design of biomass mixed fuel and provide a theoretical basis for the better development of biomass mixed fuel industry.
